Auto merge of #339 - JustForFun88:update_hashbrown_doc_3, r=Amanieu
Auto merge of #339 - JustForFun88:update_hashbrown_doc_3, r=Amanieu

Improving documentation. Part 3.

Continuation of #328 and #331.

Also I made some changes in the previously added examples (made `compute_hash` generic and rename `compute_hash` to `make_hasher` in `insert_with_hasher example`)

rust-lang/hashbrown,rust-lang/hashbrown